Railway signaling apparatus



Nov. 26, 1940. c. E. STAPLES ET AL .2 9

RAILWAY S IGNALING APPARATUS Filed May 24, 1940 C90 Fig lb.

INVENTORS Crawfapa'fiiSzaplem axial 541 1 52141 omlz i Qua 5. 71762143 A ORNEY Patented Nov. 26, 1940 UNITED STATES 2,223,078 I I RAILWAY SIGNALING APPARATUS Crawford E. Staples, Edgewood, and Harry E.

Ashworth, Wilkinsburg, Pa.; said Ashworth assignor to said Staples Application May 24, 1940, Serial No. 336,950

7 Claims.

Our invention relates to railway signaling apparatus and more specifically to apparatus of this type employing a thermal element which operates an arm signal or other indicator device. Apparatus embodying our invention is well adapted for, though in no manner limited to, the operation of signals and indicators of a model or miniature railway system such as is capable of duplicating on a reduced scale the intricate operations of a full-sized railway signaling system.

One object of our invention is to provide a simple, reliable, and relatively inexpensive arm signal or indicator as well as the track circuit control therefor. A further object of our invention is to eliminate all windings, magnets or solenoids, and movable linkages or mechanical operating connections from the signal in order to provide a structure of maximum simplicity and a minimum number of parts. A still further object is to provide a unit which can readily be transformed from a normally energized to a normally deenergized type of signal or vice versa; from an upper quadrant to a lower quadrant signal; and from a two-position to athree or fourposition signal.

We accomplish the foregoing objects by employing, among other features, a thermal element which performs the functions of the signal motor, either directly or by means of a separate 3 heater unit, the signal control current being conducted through a novel cam arrangement which is interconnected with the track circuit control apparatus.

We shall describe several forms of apparatus 5 embodying our invention and shall then point out the novel features thereof in claims.

In the accompanying drawing, Fig. 1 shows one form of apparatus embodying our invention, in which a normally energized three-position 40 type of signal controlled automatically from the track is illustrated. Figs. 1a. and 1b are two modifications of the track circuit shown in Fig. 1, for changing the signal of Fig. 1 into a two-position normally energized signal, also embodying 45 our invention. Fig. 2 shows the three-position normally deenergized modification of the signalof Fig. 1, also embodying our invention. Fig. 3 is a modification of the apparatus of Fig. 1, also embodying our invention, in which a separate 50 heater controls the operation of the signal.

Similar reference characters refer to similar parts in each of the several views.

Up to the present time, semaphore type signals for miniature railways have involved con- 55 siderable complication because these signals have usually been operated by a motor or. solenoid. Due to the requirement of small size and delicate construction of such signals, it has been difficult to build a reliable magnet-operated or motoroperated semaphore signal which would, at the 5 same time, be relatively inexpensive. By utilizing a thermal element as the driving unit, we have been able to provide a simple, rugged and thoroughly reliable "signal which can be built to very small dimensions, if desired.

Referring to Fig. l of the drawing, We have shown a stretch of track D-E divided by insulated joints in one rail to provide two adjoiningtrack circuit sections IT and 2T. One terminal B of a suitable source of current is connected 15v through a current limiting resistor R to each insulated rail section, the other terminal C of the source being connected to the other rail. Each track circuit is provided with a track relay TR which is normally energized from its respective 20 track circuit provided no train is occupying the associated track section. Entry of a train into the section DE from the left will first deenergize relay ITR, then both ITR and 2TB will be deenergized, followed by pickup of I'IR, and 25 finally both relays will be energized as the train passes completely out of. the section D-E. Passage of the train operates the contact fingers 2 and 3 of relays I'I'R and 2TB. which control the operation ofv the semaphore signal S. I

The signal S comprises a rotatable shaft 6 supported in suitable bearings which are not shown for simplicity, and has aflixed thereto a semaphore blade I whose downward movement is limited by a fixed stop8 when the signal is de-,- energized and is occupying the stop position, as shown in the drawing. The motor element of the signal comprises a thermal unit 9 having its outer end fixed to a stationary support ID and having its inner end fixed to the shaft 6 for transmitting 40 rotation thereto in the counterclockwise direction (as viewed in the drawing) when the thermal unit contracts upon heating, and in the clockwise direction when the unit expands upon cooling. The thermal unit 9 may consist of the usual bi metallic strip such as steel-invar, for example, and its resistance will be chosen such as to develop suflicient heat to operate the signal effectively.

The shaft B carries a cam ll affixed thereto which has segments l2 and I3 cooperating with suitably fixed contacts C45 and C90 for the purpose of interrupting the current in the thermal unit when the blade 1 reaches its 45 degree and 90* degree position, respectively, as will be appartrical circuit for heating the thermal unit passes from one terminal B of. the source, through contact fingers 2 and 3 of relays 'ITR, and 2TB, wire I4 andcontact C90 (or wire I5 and contact C65,

depending on trafiic conditions), cam I I, shaft 6, and thermal unit 9, to the other terminal C of the source.

Normally, when no train is occupying the section, both relays I'IR and 2TB. will be energized so that front contacts 2 and 3 l will both be closed. Under this condition,-heating current for I will begin to move upward-due to counterclockwise rotation of the shaft. This motion will continue until the segment I3 breaks contact with the finger C and interrupts the heating current at substantially the 90 degree position of the semaphore. The blade will continue to move slightly after the current is cut oif, j but this movement is scarcely perceptible'and of no consequence. As soon as the thermal unit cools somewhat,contact with segment I3 will be reestablished whereupon heating currentwill again flow for an interval of time, causing segment I3 again to leave the finger C90, whereupon the cycle is repeated until such time as a train enters the section. The periodic cooling and heating of the thermal unit results in a, scarcely perceptible movement of the blade at the 90 degree position, butthis movement occurs so slowly and is so slight as to be wholly unobjectionable, in practice.

When a train enters the track circuit IT, relay I TR will release and the signal operating currentwill becompletely interrupted atthe front contact 2 whereupon the thermal unit Will cool, causing the signal to assume its danger position as illustrated in the drawing.

12', through the remaining portions of the signal, as before.

Accordingly, the blade 7 will attain a 4l5 degree position at which point the circuit between finger. C and segment I2 will become interrupted, only to be re-established a moment later due to temporarycooling of the heater unit.

The signal will nowindicate caution for any following train. of thesemaphore in the 45 degree position will be similar to that described for the degree position. The current required by the thermal unit is so small as to cause noappreciable arcing or burningatthe contacts C45 and C90.

When the train completely vacates the track circuit 2T, relay ZTR. will pickup and in so doing will re-establish the 90 degree operating circuit for the signal so that the semaphore will indicate proceed for following trafiic. l

.The' spiral should preferably be so designed and adjustedthat in the deenergized position of the signal, as shown in Fig. l, the blade I will exert a certain amount of pressure against its stop 8.

This'trapped pressure,ywith.the spiral cold, aids in equalizing the pickup and release time of the signal by shortening the [time required for the blade to reach its stop position. Although the spiral form of the thermal unit9 is preferred, it is obvious that this unit may be normally flat,

The slight periodic movement partly curved, or take on any other suitable form, and be connected withthe semaphore either directly or through a suitable linkage, the main consideration being that the thermal unit when heated produce sufiic'ient movement to actuate the semaphore. 1 7

Referring now to Fig. let, this figure shows a track circuit which may be used in conjunction with the semaphore signal of Fig. 1 to provide atwo-position normally energized signal system. No track relays are required in this modification and finger C45 is unnecessary since the signal provides only the stop and the proceed indication. The track section DI-EI is provided with the usual track circuit ITa, as in Fig. 1, except that this circuit does not include a track relay, the current being conducted directly from the rail into the thermal unit over the 90 degree finger and cam segment.

When the section DI-EI is unoccupied, signal operating current will flow from terminal B, through resistor R, the lower rail, wire I6, finger C9D, segment I3, shaft 6, and thermal unit 9 to the other terminal C, as before. This will cause the semaphore to assume its proceed position, as will be apparent from the previous description. When a train enters the section DI EI, the signal operatingcurrent will be largely shunted away from the thermal unit by virtue of the low resistance path through the wheels and axles of the train, with the result that this unit will cool and in so doing will cause the signal to assume its stop position. As soon as the train leaves the section, the, shunt will be removed so that the signal will again be operated to its 90 degree or proceed position.

If it is desired to energize a two-position, normally energized signal over an independent circuit, as in Fig. 1, then the track circuit of Fig. 1b may be used. This track circuit ITb is similar to the track circuit IT of Fig. 1 with the eXcep-. tion that the signal operating wire I4 is connected directly with the front contact 2 of relay ITRb, without the interposition of contacts of the second relay. The C45 contact finger of. the signal may be dispensed with, as before, since only a two-position signal is desired.

Entry of a train into the track circuit D2-E2 will release relay ITRb, to deenergize the signal so that it will indicate stop. Departure of the train from the section will cause the track relay to pick up, re-establishing the proceed signal indication.

Referring to Fig. 2, the system illustrated therein includes a three-position normally deenergized blade I when heating current flows in the spiral.

It will be understood, of course, that if the thermal unit is reversed on the shaft so that the direction of decreasing spiral is opposite to that shown, then the thermal unit 9 of Fig. 1 may be used interchangeably in both Figures 1 and 2. For simplicity, the spirals in all of the figures have been shown wound in the same direction.

With the track sections IT and 2T both unoccupied, as shown in the drawing, no circuit exists over which operating current may flow to the thermal unit 9a. Accordingly, this unit is in its normal or contracted condition in which a counterclockwise force is exerted to hold the semaphore in the proceed position against the stop 8.

When the train enters section IT, an obvious circuit will be closed for operating current to flow from one terminal B, through the thermal unit 9a and segment I3, zero contact CO, wire I4, lower track rail, wheels and axles of the train, and the upper rail, to the other terminal C of the source. The operating current will cause the thermal unit to expand, whereupon the semaphore will move clockwise until the segment I3 breaks contact with the finger G0 which will occur in the horizontal or stop position of the semaphore. The signal will therefore remain at stop as long as the train occupies section IT.

When the train vacates section IT, the signal will begin to return to its normal position but since at that time a circuit is established for operating current to flow over wire I5, contact C45, and segment I2, by virtue of the wheel and axle path in section 2T, the signal will assume its 45 degree or caution position and will remain in this position as long as the train occupies the section.

When the train passes completely out of section 2T, operating current for the thermal unit will be completely interrupted so that the signal will then be restored to its proceed position in which it is shown.

Obviously, the three-position signal of Fig. 2 can be readly transformed into a signal of the two-position type by removing any part of the 45 degree control circuit, such as wire I5 or contact C45. Similarly, this signal can be transformed into one having four or more positions by adding a segment to the cam II, suitably spaced from the segments II and I2, and making contact through the proper arc of movement with a contact finger similar to C45 which would be connected with the lower rail of the section immediately in advance of section 2T. In this manner, four-position, three block signaling can be obtained in an extremely simple and inexpensive manner. It will be understood that for multipleposition signaling, the 45 degree segment as well as the Zero segment may be spaced differently and have different lengths than shown in the drawing for the three-position signal.

It will also be clear that any of the foregoing upper quadrant signals can be transformed into signals operating in the lower quadrant by suitably positioning the semaphore with respect to the shaft 6 and suitably designing and positioning the cam II on this shaft so that the current will be interrupted when the semaphore reaches the desired position.

Referring to Fig. 3, the signal Sb shown in this figure and the track circuit control therefor are identical with the arrangement shown in Fig. 1 except for the provision of a separate heater element H for the thermal unit 9. Instead of passing current through the thermal unit itself, as in Fig. 1, this current is passed through a heater H suitably placed with reference to the thermal unit 9 so 'as to provide eflicient heat transfer thereto.

With both relays ITR and 2TH picked up (section unoccupied) operating current will flow from terminal B, over contacts 2 and 3--4, wire IA, finger C90, segment I3, shaft 6, shaft-engaging contact I'I, wire I8, and heater H, to the other terminal C of the source. The operation of the signal for this condition as well as for the other trafiic conditions will be clear from the description of Fig. 1, so that this description need not be repeated.

Instead of contact II, it may be preferable under certain conditions to provide a flexible or spiral'connection from wire I8 to shaft 6, in order to decrease the friction load on the shaft as well as to eliminate contact resistance. Also, in some cases it may be desirable to connect the heater H electrically with the spiral 9 so that the spiral will contribute a certain amount of heat due to current passing therethrough to that developed by the heater H. In this manner, a shorter spiral or one of lower resistance than otherwise, can be used. The thermal unit may therefore comprise not only a current carrying thermostatic element as in Figs. 1 and 2, but also the combination of a heater and thermostatic element, as in Fig. 3, in which either the heater alone or both the heater and thermostatic element carry current.

From the foregoing description, it will be apparent that we have provided a signaling system including a novel and highly simple form of signal as. well as novel track circuit control therefor. The elements of the signal are simple, few in number, and are such as to permit transformation of the signal from one having two positions to one having three or more positions, and vice versa, with a minimum of effort or vadditional parts. A transformation from an upper to a lower quadrant signal is similarly made with ease. Moreover, the signal is such as can be operated directly from the track, without relays, by means of a simple circuit. The signal is also such as can be built to very small dimensions for miniature railway work, thus making it possible toplace the signal on a signal bridge or in some other restricted location, which cannot be done with the usual type of miniature semaphore signal. The foregoing advantages make possible a signaling system which is eflicient, reliable, and relatively inexpensive to manufacture.

Although we have herein shown and described only a few forms of railway signaling apparatus embodying our invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of our invention.

Having thus described our invention, what we claim is:

1. A railway signal comprising in combination, a thermostatic element, a semaphore normally occupying a first position and actuated by said element to a second position which it maintains as long as said element remains heated, a contact also actuated by said element and closed during a predetermined movement of said semaphore, and means including said contact for at times supplying current to heat said element to thereby cause said semaphore to be actuated to said second position.

2. A railway signal comprising in combination, a thermostatic element, a semaphore operatively connected with said element for actuation thereby, a contact actuated by said element and closed during a predetermined movement of said semaphore, and means including said contact for sup-- plying current to heat said element to thereby cause actuation of said semaphore to a predetermined position, said contact opening at said predetermined position and becoming reclosed upon a slight return movement of said semaphore due to cooling of said element to thereby maintain the semaphore substantially 'in said predetermined position. I

3. An indicating device for railways comprising in combination, a thermal element movably responsive to heat developed by current flowing therethrough, an indication member normally occupying a first position and actuated by said element to a second position whichit maintains as long as said element remains heated, a contact actuated by said element and closed during a predetermined movement of said indication member, and means including said contact for supplying heating current to said thermal element.

4. A heat responsive indicating device comprising in combination, a conducting thermostatic spiral which is movably responsive to heat developed by current flowing therethrough, an indication member normally occupying a first position and actuated by said spiral to a second position which it maintains as long as said spiral remains heated, a contact actuated by said spiral and closed during a predetermined movement of said indication member, and means including said contact for supplying heating current to said thermostatic spiral.

5. A signal for miniature railways comprising in combination, a bi-metallic element movably responsive when heated, a semaphore normally occupying a first position and actuated by said element to a second position which it maintains as long as said element remains heated, a contact actuated by said element and closed during a predetermined movement ofsaid semaphore, and means including said contact for supplying current to heat said bi-metallic element.

6. A railway signal comprising, in combination, a thermal element 7 vmovably responsive when heated, a semaphore actuated by said element, said element being so adjusted that in the absence of heat said element exerts a return force suflici-ent to positively restore said semaphore to an initial position without fully expending said return force, a contact actuated by said element and closed during a predetermined movement of said semaphore away from said initial position, and means including said contact for supplying current to heat said thermal element to thereby actuate said semaphore to a second position which it maintains as long as said element remains heated.

7. A railway signal comprising in combination, a thermal element movably responsive when heated, a semaphore normally occupying a first position and actuated by said element to a second position which it maintains as long as said element remains heated, current control means responsive to movement of said element and effective during a predetermined movement of said semaphore, and a circuit governed by said means for supplying current to heat said thermal element.

CRAWFORD E. STAPLES. HARRY E. ASI-IWORTH. 

